The research team, led by Zhichang Jing of Qingdao Agricultural University together with colleagues from Shandong Huibang Bohai Agriculture Development Limited Company, ran their experiment under a winter wheat–summer maize rotation, the dominant double-cropping system of the region. They compared two nitrogen levels, a conventional 270 kilograms of nitrogen per hectare and a reduced rate of 210 kilograms per hectare, crossed with three straw incorporation rates: no straw at all, 5,000 kilograms per hectare, and 10,000 kilograms per hectare. Over three years they tracked how each combination reshaped the soil’s physical architecture, its chemistry, its enzyme machinery, and ultimately the bacterial communities that govern whether carbon entering the soil is locked away or breathed back out into the atmosphere as carbon dioxide.

The standout treatment was the one the researchers labeled N2S1, the reduced nitrogen dose paired with the half-rate straw application. This combination achieved the highest soil organic carbon sequestration efficiency of any treatment tested, outperforming the conventional high-input practice of full nitrogen with full straw by 6.4 percent. That margin may sound modest, but in the world of soil carbon accounting, where gains of even a few percent over whole rotations are considered meaningful, a 6.4 percent improvement achieved while cutting fertilizer use is a striking result. It means more of the carbon in the straw ended up stored in the soil rather than lost, and it was accomplished with 60 kilograms less nitrogen per hectare each year.

What makes the finding technically interesting is the mechanism the authors uncovered. The winning treatment did not simply dump more carbon into the ground. Instead, it changed the fate of the carbon that was already flowing through the system. Soils under the reduced-nitrogen, half-straw regime developed more large macro-aggregates, the soil clumps larger than two millimeters that act as tiny vaults, physically shielding organic matter from decomposer microbes. The team also detected a shift toward more recalcitrant carbon fractions, the chemically stubborn forms of organic matter that resist breakdown for years or decades. Infrared analysis of organic carbon functional groups confirmed this chemical hardening of the soil’s carbon stock.

The key to this transformation, the researchers argue, lies in microbial stoichiometry, the balancing act microbes perform between the carbon and nitrogen available in their food. When nitrogen became scarcer under the reduced application rate, soil enzymes told a clear story: the ratio of carbon-acquiring to nitrogen-acquiring extracellular enzyme activity rose from 0.393 under the conventional treatment to 0.414 under the reduced-nitrogen regime, signaling intensified microbial nitrogen limitation. Faced with a nitrogen shortage, the microbial community ramped up its carbon-cycling enzymes, with xylanase activity increasing by 15.9 percent and beta-glucosidase by 13.2 percent. This pattern fits what soil ecologists call microbial nitrogen mining, a strategy in which microbes invest extra enzymatic effort to extract nitrogen from organic matter, and in doing so process carbon more thoroughly and incorporate it more efficiently into their own biomass and residues.

DNA sequencing of the soil bacterial communities added a second layer of evidence. Under the optimal treatment, the community shifted toward oligotrophic taxa, the patient, slow-growing specialists such as Acidobacteriota and Chloroflexi that thrive when nutrients are scarce rather than abundant. These are precisely the organisms that tend to convert carbon into stable microbial necromass rather than releasing it quickly through respiration. Network analysis of the community revealed something equally telling: the bacteria under the reduced-input treatment formed a more complex and cooperative co-occurrence network, with more connections linking species to one another. A richer web of microbial interactions is often associated with more stable ecosystem functioning and more efficient resource cycling, suggesting the treatment did not just change who lived in the soil but how the residents worked together.

The broader significance of the study lies in the sheer scale of the resource at stake. Saline and salt-affected soils are among the most extensive degraded land types on the planet, and much of that area sits in agricultural regions where straw burning or removal is common practice. Incorporating straw into such soils has long been promoted as a way to build organic matter, but it carries a well-known risk: fresh crop residues can stimulate microbes to decompose existing soil organic carbon as well, a phenomenon called priming that can erase the intended gains. High nitrogen availability is thought to worsen this problem by relieving the microbial nitrogen limitation that would otherwise force careful, conservative carbon processing. The new results suggest that deliberately maintaining a degree of nitrogen scarcity, calibrated against the carbon-to-nitrogen ratio of the added straw, can tip the balance away from respiratory carbon loss and toward stabilization.

There are also practical and economic dimensions worth noting. Nitrogen fertilizer is one of the largest recurring costs in cereal production and a major source of agriculture’s greenhouse gas footprint, both from the energy used to manufacture it and from nitrous oxide emitted from fertilized fields. A management recipe that achieves better carbon sequestration while trimming nitrogen inputs by roughly 22 percent offers a rare double dividend: lower costs for farmers working marginal land and reduced emissions intensity for the cropping system as a whole. Because the approach relies on adjusting rates of two inputs that farmers already manage, rather than requiring new technologies or amendments, it could in principle be adopted widely across salt-affected wheat-maize regions without significant infrastructure investment.

The authors are careful to frame the strategy as biologically driven, and that framing matters. Rather than relying on chemical stabilization or mineral associations alone, the treatment works by steering the soil’s living community toward a metabolic regime that favors carbon retention. Aggregate formation provides the physical protection, recalcitrant carbon fractions provide the chemical durability, and a nitrogen-limited, cooperative microbial community provides the biological engine that channels straw carbon into both. As the researchers conclude, moderately reduced nitrogen input combined with half-dose straw incorporation optimized the carbon-to-nitrogen stoichiometric balance, redirecting microbial metabolism from respiratory carbon loss toward aggregate-mediated physical protection. For the billion-plus hectares of salt-affected soil worldwide, that is a recipe worth testing far beyond the Yellow River Delta.

Subject of Research: Soil organic carbon sequestration through straw incorporation and reduced nitrogen fertilization in saline soils

Article Title: Synergistic straw incorporation and reduced nitrogen application enhance soil carbon sequestration in saline soils

Article References: Jing, Z., Zhang, L., Han, J., Ma, C., Zhang, S., Sun, H., & Ding, X. (2026). Synergistic straw incorporation and reduced nitrogen application enhance soil carbon sequestration in saline soils. Plant and Soil. https://doi.org/10.1007/s11104-026-09056-8

Image Credits: AI Generated

DOI: 10.1007/s11104-026-09056-8

Keywords: soil organic carbon, saline soil, straw incorporation, nitrogen fertilization, microbial nitrogen mining, enzyme stoichiometry, soil aggregates, bacterial community, Yellow River Delta, carbon sequestration, soil microbiology, sustainable agriculture

Arbuscular mycorrhizal fungi, or AMF, are among the most successful symbionts on Earth, forming associations with roughly 80 percent of plant species, including most agricultural crops. These fungi penetrate or envelop plant roots and extend a web of filaments, called extraradical mycelium, far into the surrounding soil. Through this network they draw in water and hard-to-reach nutrients, particularly phosphorus, whose poor mobility in soil often limits crop growth. In exchange, the plant supplies the fungus with carbon derived from photosynthesis. For decades, agronomists have exploited this partnership to improve crop tolerance to drought, salinity, and nutrient poverty, but the consequences for the wider rhizosphere microbiome, the teaming bacterial ecosystem hugging the root surface, have remained poorly resolved, especially under low-nutrient conditions.

To probe this question, the research team grew tobacco, Nicotiana tabacum, in pots filled with a low-fertility loess-derived soil collected near the university in Anhui Province. The soil was deliberately lean: ammonium nitrogen measured just 3.37 milligrams per kilogram and nitrate nitrogen 2.16 milligrams per kilogram, with modest organic matter of 15.3 grams per kilogram. Before planting, the soil was autoclaved at 121 degrees Celsius for two hours to eliminate native fungi and other microbes, creating a clean slate. Half the pots received 30 grams of an inoculum containing C. etunicatum spores, mycelia, and colonized root fragments at a density of five spores per gram; the control pots received an equal amount of sterilized inoculum to keep background conditions identical. The plants then grew for 60 days in a greenhouse cycling between 28 and 18 degrees Celsius, with three biological replicates per treatment.

The growth results were unambiguous. Compared with uninoculated controls, AMF-colonized tobacco showed significantly greater aboveground and belowground fresh weight and taller plants, with root biomass increasing by 12.90 percent and spore density in the soil rising by 4.51 percent. More striking were the changes inside the plant’s stress-response machinery. Activities of the antioxidant enzymes catalase and superoxide dismutase rose significantly, while levels of malondialdehyde, a molecular marker of lipid peroxidation and membrane damage, fell. Because malondialdehyde accumulates when reactive oxygen species assault cell membranes under stress, its decline indicates that the fungal partnership had measurably blunted the oxidative injury that nutrient scarcity inflicts on tobacco tissue.

To see whether these physiological gains were mirrored in the root-zone microbiome, the team sequenced the V4 region of the bacterial 16S rRNA gene from rhizosphere soil using the Illumina MiSeq platform, processing the reads through the Deblur pipeline to generate amplicon sequence variants. Phylogenetic analysis of the 100 most abundant genera identified twelve core bacterial phyla, dominated by Proteobacteria with 28 genera, Chloroflexi with 16, Actinobacteriota with 14, and Myxococcota with 12. Fungal inoculation significantly reshaped the community structure, enriching beneficial groups across these phyla. Among the genera that shifted most dramatically, the AMF-treated soils favored unclassified members of the Xanthomonadaceae along with Agromyces, Phenylobacterium, and Solimonas, whereas the control soils were dominated by Arenimonas, Sphingoaurantiacus, and Azohydromonas.

Each enriched phylum brings a distinct ecological skill set. Proteobacteria, among the most diverse bacterial phyla known, act as central regulators of global carbon, nitrogen, and sulfur cycling, and their nitrogen-fixing members can enhance soil fertility through nitrification-related processes. Actinobacteriota solubilize phosphorus and mineralize organic nutrients while producing extracellular metabolites that suppress pathogens and sometimes function as growth regulators. Chloroflexi, filament-forming anaerobes that degrade complex carbohydrates and peptides, likely metabolize the organic deposits left by fungal hyphae, explaining their rise in the mycorrhizal rhizosphere. Myxococcota, meanwhile, are predators within the mycelial food web, consuming the carbon-rich compounds that AMF transport from the plant. Together, these groups form a functional support crew whose presence correlates with improved nutrient acquisition and stress tolerance in the host.

Perhaps the most visually compelling evidence came from co-occurrence network analysis, which maps which bacterial taxa tend to appear together and infers cooperative or competitive relationships. The networks differed sharply between treatments. Although the control network contained slightly more nodes and edges, the AMF network showed a higher average clustering coefficient, 0.713 versus 0.705, and, critically, far fewer negative correlations between species. In the control network, 96.13 percent of nodes were peripheral with little topological significance, while the AMF network pushed that proportion to 97.31 percent but concentrated its interactions more centrally, with node-level measures of degree, betweenness, and modularity all significantly higher. The researchers interpret this architecture as evidence that fungal inoculation drives the community toward greater microbial synergy, with more positive, mutualistic links replacing antagonistic ones.

Functional profiling reinforced the picture. Using STAMP statistical comparisons, the team found that seven representative microbial functions differed significantly between treatments, with AMF-treated soils showing enhanced abundance of genes associated with signal transduction and prokaryotic cell communities. Mantel tests revealed that bacterial alpha diversity was tightly linked to cell motility, signal transduction, and prokaryotic community functions, with correlation coefficients exceeding 0.20 at statistical significance. The strongest positive functional correlations appeared among amino acid metabolism, carbohydrate metabolism, and cofactor and vitamin metabolism, suggesting that the enriched community was not merely more diverse but metabolically more capable.

To tie these threads together causally, the researchers built a structural equation model linking the fungus, bacterial network structure, soil and plant enzyme activity, community diversity, community function, and plant antioxidant capacity. The model showed that AMF exerted strong positive effects on bacterial network structure, with a standardized path coefficient of 0.840, and on soil enzyme activity, at 0.573, both highly significant. Plant enzyme activity positively influenced both bacterial community function and the plant’s antioxidant capacity, while bacterial community diversity and function in turn boosted antioxidant defenses. Notably, bacterial community diversity exerted a stronger total effect on antioxidant capacity than the fungus itself, implying that the fungus works largely through its microbial intermediaries rather than on the plant directly.

The implications extend well beyond tobacco, a crop of substantial economic importance in China and one of the most intensively studied mycorrhizal hosts. As agriculture confronts the twin pressures of rising fertilizer costs and the environmental toll of over-application, biological strategies that coax more productivity from lean soils are increasingly attractive. This study demonstrates that a mycorrhizal inoculant does not simply feed the plant; it curates a bacterial entourage, recruiting nutrient cyclers, pathogen suppressors, and carbon scavengers while knitting them into a stabler, more cooperative network. The finding that community diversity, not the fungus alone, is the strongest driver of antioxidant protection suggests that future biofertilizers may need to be designed as ecosystems rather than single strains. For now, the humble threads of a soil fungus have been shown to conduct an entire underground orchestra, and the plant, quite literally, reaps the benefits.

Subject of Research: Effects of arbuscular mycorrhizal fungal inoculation on the rhizosphere bacterial community and antioxidant capacity of tobacco under low-nutrient conditions

Article Title: Effect of Claroideoglomous etunicatums on rhizosphere bacterial community of tobacco under low nutrient conditions

Article References: Chen, J., Geng, X., Zhang, Q., Lin, K., Li, Z., Wang, B., Xiao, Q., & Li, X. (2025). Effect of Claroideoglomous etunicatums on rhizosphere bacterial community of tobacco under low nutrient conditions. Advanced Biotechnology, 3(3), Article 22. https://doi.org/10.1007/s44307-025-00071-x

Image Credits: AI Generated

DOI: 10.1007/s44307-025-00071-x

Keywords: arbuscular mycorrhizal fungi, Claroideoglomus etunicatum, tobacco, rhizosphere, bacterial community, 16S rRNA sequencing, co-occurrence network, antioxidant enzymes, malondialdehyde, soil microbiome, low nutrient stress, structural equation modeling

The research team set out to answer a deceptively simple question: how does temperature affect the abundance and composition of antibiotic resistance genes in activated sludge systems, when everything else is held constant? This question matters because real-world treatment plants experience seasonal swings, and previous field studies have struggled to disentangle the effects of temperature from the effects of changing influent composition. Winter brings not only colder basins but also different patterns of water use, different chemical loads, and different microbial communities arriving at the plant. To isolate temperature as a single variable, the researchers designed an elegant controlled experiment conducted directly at an urban wastewater treatment plant in Portugal, ensuring that the wastewater feeding their experimental systems reflected genuine, real-world conditions rather than synthetic laboratory mixtures.

Two laboratory-scale conventional activated sludge systems were operated side by side for 147 days under identical conditions, with one crucial exception. The control system was maintained at approximately 20 degrees Celsius, a temperature representative of moderate operating conditions, while the test system was run sequentially at 10, 5, 15, and 28 degrees Celsius. This sequential design allowed the researchers to observe how the same microbial community responded as the thermal regime shifted up and down over time. Throughout the experiment, the team sampled the feed, which consisted of primary effluent from the host treatment plant, as well as the treated effluent and the sludge from each system. These samples were analyzed for physicochemical parameters, fecal indicator bacteria, the abundance of specific antibiotic resistance genes, and the composition of the bacterial communities using molecular profiling techniques.

The results revealed a striking interplay between what enters the plant and what happens inside it. The patterns of antibiotic resistance genes in the treated effluent were clearly influenced by the composition of the incoming feed, confirming that influent characteristics drive much of the resistance dynamics in activated sludge systems. However, temperature exerted an additional, independent influence on top of this influent-driven variability. The most dramatic effect emerged when the test system was operated at 5 degrees Celsius. Under this cold regime, the abundance of intI1, a gene widely used as a proxy for anthropogenic antibiotic resistance pollution and a marker of mobile genetic elements, dropped significantly compared with the control system held at 20 degrees Celsius.

Even more importantly from a clinical standpoint, the cold treatment significantly reduced genes of direct medical relevance, including blaIMP, which confers resistance to carbapenem antibiotics, a last-resort class of drugs used against multidrug-resistant infections, and qnrS, which is associated with reduced susceptibility to fluoroquinolones. These are not obscure genetic markers; carbapenem resistance in particular represents one of the most alarming developments in infectious disease medicine. The observation that a simple operational parameter like temperature could measurably suppress these genes in treated effluent carries substantial implications for how treatment plants might be managed to limit the environmental dissemination of resistance.

To understand why cold temperatures had this effect, the researchers turned to the bacterial community composition data. The shifts in gene abundance were associated with changes in the microbial community itself, particularly a decrease in genera such as Acinetobacter and Escherichia-Shigella, both of which are considered potential hosts for antibiotic resistance genes and both of which include clinically significant pathogens. In other words, the cold did not simply disable the genes while leaving their carriers intact; it appears to have reduced the fitness of the key bacterial hosts that harbor and propagate these genes. When the host organisms decline, the genes they carry decline with them, offering a mechanistic explanation for the observed reductions in effluent ARG loads.

An equally important finding concerned where in the system these effects occurred. The researchers found no significant differences in antibiotic resistance gene abundance in the sludge fraction between the cold and control systems, indicating that temperature mainly influenced ARG persistence in the liquid phase. This distinction matters because the liquid effluent is what gets discharged into receiving rivers and coastal waters, while sludge is typically handled separately, often through anaerobic digestion and land application. The selective reduction of ARGs in the liquid phase suggests that low-temperature operation specifically curtails the release of resistance genes into the aquatic environment, which is one of the principal pathways by which resistance spreads from human settlements into natural ecosystems.

The temperature effect extended beyond resistance genes to the removal of fecal indicator organisms. Reductions of Escherichia coli, the standard marker of fecal contamination, were significantly greater at 5 degrees Celsius than at the control temperature, indicating that cold operation also enhanced the removal of this pathogen indicator from the effluent. This finding adds to the appeal of cold operation from a water quality perspective, although the researchers caution that the picture is not uniformly positive. Low temperature impaired nutrient removal, a critical function of activated sludge systems that protects receiving waters from eutrophication. Nitrifying bacteria and other nutrient-cycling microorganisms are notoriously sensitive to cold, and their slowed activity under low-temperature conditions translated into poorer nutrient removal performance.

Crucially, however, the overall effluent quality remained within discharge limits even during the cold-temperature runs, meaning that the trade-off between enhanced ARG suppression and reduced nutrient removal did not push the system out of regulatory compliance in this study. This balance is central to any practical consideration of the findings. Treatment plant operators cannot simply chill their reactors without consequence, but the study demonstrates that the penalty may be more manageable than feared, while the benefit, a significant reduction in clinically relevant resistance genes entering the environment, could be substantial. The authors frame temperature as an important operational driver of antibiotic resistance dissemination, a variable that deserves deliberate attention rather than passive acceptance.

The broader significance of this work lies in its contribution to the growing field of evidence-based wastewater management for antibiotic resistance control. As concerns mount over the role of treatment plants as conduits for resistance genes into rivers, irrigation systems, and drinking water sources, engineers and regulators are searching for interventions that are feasible within existing infrastructure. This study suggests that temperature, a parameter already monitored and in some contexts already manipulated, could be part of that toolkit, particularly in climates or seasons where colder operation is achievable. It also underscores a fundamental ecological principle: the fate of antibiotic resistance genes in engineered environments is governed not only by the genes themselves but by the fitness of the microbial communities that carry them. By shifting the thermal environment, operators can shift the competitive balance of those communities, and with it, the resistance burden flowing out of the plant and into the world downstream.

Subject of Research: Effect of temperature on antibiotic resistance gene dynamics in conventional activated sludge wastewater treatment

Article Title: Influent-driven antibiotic resistance dynamics are constrained by low temperatures in conventional activated sludge systems

Article References: Influent-driven antibiotic resistance dynamics are constrained by low temperatures in conventional activated sludge systems. (n.d.). https://doi.org/10.1007/s00253-026-14036-0

Image Credits: AI Generated

DOI: 10.1007/s00253-026-14036-0

Keywords: antibiotic resistance genes, wastewater treatment, activated sludge, temperature, intI1, blaIMP, qnrS, Escherichia coli, Acinetobacter, bacterial community, nutrient removal, environmental microbiology

The research team, led by Phishet Sungtong and Daoroong Sungthong, compared conventional composting with vermicomposting, a mesophilic process in which the African nightcrawler earthworm Eudrilus eugeniae works alongside microbes to decompose organic matter. Each reactor contained a carefully balanced feedstock of cow manure and discarded cabbage at a ratio of 89:11 on a dry-weight basis, with some reactors receiving 7 grams of cut PLA/PBAT bag pieces, equivalent to 1 percent of the initial dry mass. The bags, collected from a campus café, were cut into 5 by 5 centimeter squares following the specimen preparation procedure of ISO 20200, the international standard for laboratory-scale disintegration testing. Twenty-eight independent reactors were prepared, with destructive sampling at days 15, 30, 60, 90, and 120.

The temperature story turned out to be central. Conventional composting initially peaked at 27 to 28 degrees Celsius before stabilizing near ambient levels, while vermicomposting held a strictly mesophilic profile of 24 to 26 degrees throughout, a range chosen to keep the earthworms alive and reproducing. Neither system reached the thermophilic phase of 58 degrees Celsius that defines industrial composting, and that matters enormously for PLA. The glass transition temperature of PLA sits around 56 to 63 degrees Celsius; below it, the polymer remains glassy, with stiff chains that resist water penetration and hydrolytic chain scission. PBAT, by contrast, with a glass transition near minus 35 degrees, stays rubbery at any composting temperature, yet its aromatic terephthalate segments remain stubbornly resistant to microbial enzymes regardless.

By day 120, the recovered plastic fragments told a nuanced tale. Vermicomposting achieved a mean disintegration of 59.91 percent, compared with 55.96 percent for conventional composting, a numerically higher result of nearly four percentage points, though the ranges overlapped and the difference was not statistically distinguishable. Notably, the vermicomposting range extended to 72.97 percent, higher than any single composting reactor achieved. The researchers attribute this edge to the combined action of earthworms and microbes: worms ingest and transport plastic fragments into the drilosphere, the biologically rich zone around their burrows, and their gut passage and castings expose the polymer to dense microbial communities in oxygen-limited microsites.

Spectroscopic evidence confirmed that the mass loss was not merely physical fragmentation. Attenuated total reflectance Fourier transform infrared spectroscopy revealed a pronounced decline in the absorbance of the ester carbonyl band near 1712 wavenumbers, dropping from 0.3304 at day zero to 0.1892 in composted and 0.3083 in vermicomposted samples, alongside a sharp decrease in the carbon-oxygen-carbon stretching band. These changes signal cleavage of the ester bonds that link the polymer chains, generating terminal hydroxyl and carboxylic acid groups that microbes can then assimilate through the tricarboxylic acid cycle into carbon dioxide, water, and biomass. Scanning electron microscopy showed the once bumpy, sponge-like surface progressively cracking, pitting, and peeling into layers, with rod-shaped cell-like structures colonizing the fracture grooves.

An intriguing metabolic twist emerged when the researchers compared the two systems chemically. The vermicomposting reactors received fresh frozen cabbage every 30 days to feed the worms, providing microbes with an abundant, easily digestible carbon source. Under carbon catabolite repression, microorganisms preferentially consume such favored substrates and suppress the synthesis of the extracellular depolymerases needed to attack recalcitrant plastic. The composting reactors, starved of new food after day 30, may have been driven by metabolic stress to upregulate polymer-degrading enzymes, using PLA/PBAT as an alternative carbon source. This may explain why the vermicomposted plastic showed a less pronounced reduction in ester absorbance despite its slightly greater mass loss.

Beyond the plastic itself, the study asked whether the resulting compost and vermicompost were safe and effective fertilizers. Both systems matured convincingly: the carbon-to-nitrogen ratio fell from 27.1 to between 16 and 20, meeting Thai agricultural standards, while cation exchange capacity nearly doubled, reflecting the formation of humic substances. Vermicompost proved the richer fertilizer, accumulating roughly twice the calcium of conventional compost, reaching 12.7 percent, thanks to the calciferous glands of earthworms excreting calcium carbonate in their castings, along with elevated potassium and sodium. Germination tests with mung bean seeds showed that phytotoxicity dropped rapidly, with the germination index exceeding 100 percent by day 15 and reaching 136 percent in vermicompost at day 120, compared with 101 percent for compost.

Heavy metal analysis added a cautionary note. Cadmium and lead remained below detection limits in all systems, and chromium traced back to the cabbage feedstock rather than the plastic. However, nickel appeared exclusively in the bioplastic-amended reactors, peaking at 37.78 milligrams per kilogram in vermicompost, likely derived from nickel oxide additives used in PLA manufacturing to improve tensile strength and confer antimicrobial properties. The researchers warn that lactic acid released during PLA degradation could locally acidify the matrix and mobilize nickel into plant-available forms, a dynamic that warrants environmental monitoring even though all measured values fell below Thai regulatory limits.

Bacterial community sequencing of the day-120 samples revealed sharply different microbial worlds. Compost samples hosted greater diversity, with Shannon indices above 9 and over a thousand observed amplicon sequence variants, dominated by Pseudomonadota, Bacillota, and Chloroflexota, with genera such as Lysinibacillus and Litorilinea prominent. Vermicompost samples were less diverse but enriched in Bacillota and Bacteroidota, including anaerobe-associated taxa such as Clostridium and Romboutsia, plausibly reflecting oxygen-limited microsites in earthworm guts and moist organic particles. Both Lysinibacillus and Clostridium are recognized plastisphere colonizers capable of secreting esterases and lipases that cleave polyester bonds, making them candidates for further investigation, though the authors are careful to note that their presence at day 120 does not prove direct involvement in plastic degradation.

The study’s practical message is clear: compostable does not mean gone. Under mesophilic conditions, PLA/PBAT bags lost more than half their mass in 120 days but remained incompletely disintegrated, and the bioplastic-amended compost actually failed the Thai agricultural standard precisely because macroscopic plastic fragments persisted. The authors suggest extending treatment duration, maintaining continuous thermophilic conditions, introducing specific polymer-degrading microorganisms, or employing advanced in-vessel reactors with real-time temperature and moisture monitoring to push degradation to completion. They also acknowledge the limits of their design, including single reactors for most sampling times and endpoint-only microbial analysis, which constrain statistical inference. Until such improvements arrive, the study offers consumers and waste managers a grounded benchmark: earthworms give compostable plastics a modest but measurable boost, yet the thermophilic heat of industrial composting remains the gold standard for making these materials truly vanish.

Subject of Research: Disintegration of PLA/PBAT bioplastic blends during composting and vermicomposting and the resulting fertilizer quality and bacterial communities

Article Title: Lab-scale comparison of PLA/PBAT disintegration in composting and vermicomposting: fertilizer quality, phytotoxicity, and day-120 bacterial community profiles

Article References: Sungtong, P., & Sungthong, D. (2026). Lab-scale comparison of PLA/PBAT disintegration in composting and vermicomposting: fertilizer quality, phytotoxicity, and day-120 bacterial community profiles. Environmental Challenges, 25, Article 101664. https://doi.org/10.1016/j.envc.2026.101664

Image Credits: AI Generated

DOI: 10.1016/j.envc.2026.101664

Keywords: PLA/PBAT, biodegradable plastics, composting, vermicomposting, earthworms, Eudrilus eugeniae, disintegration, FTIR, scanning electron microscopy, bacterial community, compost quality, heavy metals